"We are also developing a response plan that involves our nurses and Connections counselor so that students who may need interventions and education will have access to the necessary support," Darien High School Principal Ellen Dunn wrote in an email. "The goal, of course, is to help our students make healthy and safe decisions."

The state House of Representatives in May voted in favor of a bill that prevents minors from purchasing an "electronic nicotine delivery system" and other vapor products. The state Senate approved the bill April 24. Connecticut joined 27 states with a similar law on the books. Gov. Dannel P. Malloy signed the bill on June 3.

The U.S. Food and Drug Administration announced its own preliminary regulations in late April, which would ban the sale of e-cigarettes to anyone under the age of 18. The FDA now will review thousands of comments it received regarding the policies and make any changes as it sees fit. The regulations are expected to be finalized in 2015.

E-cigs, which were first introduced in China in 2004, heat a nicotine liquid to create a vapor that's similar to smoke. The products are marketed as a harmless way to quit smoking traditional cigarettes while still receiving nicotine. They come in a variety of flavors, including bubble gum, gummy bears, cherry and cola.

The odorless vapor is problematic in catching students in the act of "vaping," though, said Darien High School Student Resource Officer James Palmieri.

According to a 2013 Centers for Disease Control and Prevention study, the number of students in grades 6-12 who have ever tried e-cigarettes doubled during the 2011-12 school year, resulting in an estimated 1.78 million students having tried e-cigs as of 2012.

The study also found that 76.3 percent of middle- and high-school students who used e-cigarettes within the past 30 days also smoked conventional cigarettes.

In 2011, according to the CDC, 6.9 percent of all high school students reported trying e-cigarettes.